My app has a complicated set of queries, index/filters, and arrayformulas to calculate invoices for student lessons and process if they are paid or not. I observed one of my users rapid fire entering 11 lessons into the app. As soon as the records started coming into the sheet, the calculations started. It took about 10 minutes for the sheet to pull in 10 of the lessons and one did not make it at all. I watched the sheet sit and spin through calculations for about 20 minutes before it finished. I will need to go through all my formulas and try to make them more efficient. Not sure where to start since I have no way to debug the sheet and see where the hangup is. I guess I have some work to do.

This brings me to my question. Where do calculations take place in a google sheet? Some stuff I read online alluded to the fact that my computer handles calculations. Is it true that the computer will take the load off of google servers if the sheet is open? Would I have better results by keeping the sheet closed and allowing the calculations to occur on google servers? Just wondering if anybody has any deep level understanding of how google sheets handles the processing of calculations with and without the sheet open on my computer.